This invention relates to plastic-bonded cast explosives.
Most plastic-bonded explosives are based on inert binders such as polyesters, polyurethanes or polyacrylates.
The binder is typically present in from 10 to 40 weight percent of the composition, the remainder being filled with explosives such as pentaerythritol tetranitrate (PETN), trinitrophenylmethylnitramine (tetryl), cyclotrimethylenetrinitramine (RDX), cyclo-1,3,5,7-tetramethylene-2,4,6,8-tetranitramine, (HMX) etc. A great variety of other solid additives, such as oxidizers and exothermic metals have been previously employed in plastic-bonded explosives. Of course, in order to maximize explosive energy, a high degree of solids loading is desired. Solids loading is the term generally solids described above.
Typically, solids are added to the liquid binder while in monomeric form. The binder is then polymerized to form the solid explosive composition.
For various applications, such as shaped charges, the explosive must be machined into the desired shape. Obviously, processing is greatly expedited if the composition can be cast into a mold and then cured to the desired shape. However, casting requires good rheological properties and a viscosity lower than that of most binders which are highly loaded with solids.
One solution to the problem of providing a high energy yet castable explosive is to use a binder which is itself an explosive. Finger et al. in U.S. Pat. No. 3,480,490 disclose that the liquid explosive 2,2-dinitropropyl acrylate (hereinafter termed DNPA) may be mixed with HMX, polymerized to form poly DNPA, cast, and cured. Finger et al. recognized the effect of the particle size of the HMX on the fluid properties of the composition, but concluded that 20p HMX was the optimum size and that HMX content could not be increased beyond 75%.